CID processes have been used to confirm the identification of ten metabolites of diethylhexyl phthalate (DEHP), which have been isolated in small quantities as reference standards for metabolism studies. Plans are underway (at LAIR) to use 13C-labeled DEHP for studies of plasticizer pharmacokinetics in man. The role of NIEHS will be solely to analyze plasma and urine samples provided by LAIR.